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  • November 21, 2018, 07:55:14 AM

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Author Topic: Ercoupe Build (slow)  (Read 4483 times)

Offline john e. holliday

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Re: Ercoupe Build (slow)
« Reply #50 on: July 14, 2018, 11:25:04 AM »
The Plane I did the tail skid on was Pat Johnsons P-47. HB~>
John E. "DOC" Holliday
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Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #51 on: July 15, 2018, 08:58:00 AM »
Ercoupe tail wheel? All the ones I worked on had nose wheels.

That's why it'd be worrisome if I remembered the tail wheel!
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #52 on: August 05, 2018, 02:56:43 PM »
Landing gear blocks in, landing gear wire bent.  If you look closely at the inboard wing, you'll see that there's a hole drilled on the right that's been plugged -- that's because I made that one a mirror of what it should be.  Then I discovered that it would have been a hole lot easier to just make the receiver for the wire out of 1/4" plywood and drill the hole after the fact (this probably wouldn't work as well if I didn't have a drill press - but I do).

I haven't thought through the scale gear leg dressing -- I'll do that later, or I'll just leave 'em off.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #53 on: August 05, 2018, 03:02:13 PM »
I never did post a pic of my scale subject.  The documentation comes from Airborne Media.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #54 on: August 11, 2018, 06:59:50 PM »
It's a wing!  My god, but that's a lot of dihedral.  I could make this thing free flight just by leaving out the control system and maybe making the rudders bigger!

I didn't want to think too hard about how to brace the center section, so I just fiberglassed it.  The styrofoam blocks in the back is because I just wrapped the 'glass around the trailing edge, and it couldn't follow the sharp curve on its own -- so I took some foam scraps I had lying around, slit them, and used them as soft-ish clamps.  The epoxy's curing now, I'll find out if it worked tomorrow morning!
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #55 on: August 13, 2018, 09:51:17 PM »
Wing set aside for now.  On to the fuselage.  I'm equally tempted to just make it out of two honkin' big pieces of 1/2 x 3", or built up a framework out of 1/2x1/2 sticks and laminate on some skins.  Oh, the indecision.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline john e. holliday

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Re: Ercoupe Build (slow)
« Reply #56 on: August 14, 2018, 10:39:18 AM »
Does this mean you are going to put the wing in a profile ship?   Shame on you, with your talent an expertise it needs a built up fuselage. mw~
John E. "DOC" Holliday
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Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #57 on: August 14, 2018, 10:52:44 AM »
Does this mean you are going to put the wing in a profile ship?   Shame on you, with your talent an expertise it needs a built up fuselage. mw~

I spent two full months dithering over how I was going to build a full fuselage for this thing (yes, I know -- formers & planks & stop worrying).  Then I decided to just build the @#$% thing as a profile.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Chris McMillin

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Re: Ercoupe Build (slow)
« Reply #58 on: August 17, 2018, 09:12:22 PM »
Hi Tim,
I can see that. When I built the Tigercat I simply followed the plans which were elegant and easy, top and bottom keel with outer shape per the scale drawing, left and right keels with cross sectional formers, same deal with outer shape per scale drawings, then plank it with 3/16's x1/8 balsa and sand to shape. It was like building 3 fuselages though!
If you didn't have the cross sections from scale plans that could get involved. One good thing about having a profile first is that you can get a real good idea of ow it flies, how it all works, etc and then building a full fuse version would be easier.
Chris..

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #59 on: August 18, 2018, 07:05:04 PM »
Don't poke at that little bitty hole in the bathroom floor, don't put a compression gauge on that '63 Suburban you just bought for $600, and don't superimpose a picture of your scale subject on the 3-view.

Sigh.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline eric david conley

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Re: Ercoupe Build (slow)
« Reply #60 on: August 18, 2018, 08:33:08 PM »
     Hey Tim, when I look at your picture that you imposed the three view over I see that the picture was taken several feet (well maybe 1.5') above where middle of the fuselage is on three view. I don't think you can use a photograph that is taken eye height (standing) to get the prospective you would want to build a profile.  (maybe?)
Eric

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #61 on: August 18, 2018, 08:44:20 PM »
     Hey Tim, when I look at your picture that you imposed the three view over I see that the picture was taken several feet (well maybe 1.5') above where middle of the fuselage is on three view. I don't think you can use a photograph that is taken eye height (standing) to get the prospective you would want to build a profile.  (maybe?)

I could have done a better job extracting the picture, but I was lazy.

It's really the shape of the canopy -- the 3-view has it straight in front and bubbled in the back, while the real plane has a bubble in the front and straight in the back.

Yes, you can't make too many judgement beyond that.  But isn't that enough?
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #62 on: September 22, 2018, 05:56:36 PM »
Super tiny bit-o-progress -- I got the arrangement of wood in the nose figured out.  Three engine bearers (I had been thinking of going electric, but changed my mind) and the nose gear bearer.  As part of that, I figured out a nose gear arrangement that'll give me some spring without having to make anything too wacky.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #63 on: September 22, 2018, 06:01:19 PM »
I'm going to steal the general idea for the nose gear from here, except that the retainer block will need to be toward the back, because the landing forces will tend to want to pull the back of the wire out, rather than the front.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Chris McMillin

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Re: Ercoupe Build (slow)
« Reply #64 on: September 23, 2018, 10:26:47 PM »
Keep at it, man!
Chris...

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #65 on: September 29, 2018, 12:45:19 PM »
OK.  So this is utter insanity.  Working on the front landing gear, making a yoke for the wheel.  I'll make a steel collar for the top, then braze the music wire LG to the yoke.  The axle will go through a pair of 1/8" holes in the bottom of the yoke.

Even for all the work, it only sorta-kinda looks like the original, and will probably not look quite right from 10 feet away -- I just wanted an actual yoke holding the wheel, and hopefully it'll make a better impression than a hook bent out of music wire.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #66 on: September 29, 2018, 02:49:23 PM »
I love it when a plan comes together.  Ready for brazing.  Of course, we won't know for sure how good it is until the first hard landing...
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #67 on: September 29, 2018, 05:17:50 PM »
And brazed.  I need to get better at using less filler -- I think I need to ignore the directions on the can of flux, and apply flux directly to the part.  If I brazed more than once every two or three years, I'd probably be better.

The two white circles are spacers to hold the wheel centered in the yoke.  They're hand machined from solid billet cutting board.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #68 on: September 29, 2018, 07:43:13 PM »
Clamp made, mounting block drilled for clamp, T-nuts in (and I need to order more 3/4" screws!)  It's ready for glue.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline john e. holliday

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Re: Ercoupe Build (slow)
« Reply #69 on: September 29, 2018, 08:16:53 PM »
Looks good to me.    H^^
John E. "DOC" Holliday
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Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #70 on: October 03, 2018, 11:41:39 AM »
Fuselage framing in progress.  I'm going with an open framework for the rear fuselage, to be sheeted with 3/32" balsa, in hopes of getting the weight down.  Later on, when I complain about putting a ton of brass in the tail, you may all laugh and laugh.

Motor mounts and nose gear mount is in place.  I'm planning on fairly small 3/32" plywood braces that glue directly to the maple, with the balsa sheeting butted up to that.  Then I'll use honkin' big lite-ply doublers of more traditional extent over the top -- should be strong enough for stunt, & so strong enough for scale.

The bottom stick is some high-density (13.5 lb/ft3) that I had lying around -- I'm getting rid of it!  Too bad it's all behind the CG.  It needed to be bent -- it turns out that a 1/2 square piece of balsa fits nicely into a tall beer bottle filled with water and ammonia.  If you look closely you can see the water mark, about 1/5 of the way in from the right edge of the picture.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #71 on: October 14, 2018, 08:21:10 PM »
Fuse frame mostly done (there's some shaping to be done around the dashboard).  Then it gets doublers -- which I haven't fully figured out yet, because I want it strong, but I also don't want it to weigh a ton.  Then it gets sheeted with 3/32" balsa.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #72 on: October 27, 2018, 08:58:49 PM »
I was kind of unhappy about using a 40FP or 4xLA on this because the only one I have that's not mounted on a plane is one that's been modified for stunt, and I have no idea how well it'll work with a throttle on it (it's certainly down on power compared to my other similar engines).  So I was digging in my engine drawer and came up with a pair of old Fox 40's in a box.  One of them even runs.  Woohoo!  I don't have to cannibalize a plane!  And I have junker engine (the front end leaks) to use for fitting up!

They're way bigger than the OS bushed 40s.  Fortunately, I had been planning on using motor mount pads anyway, so I just made a different set of pads.  The engine fits, after a very slight trimming to the bearers, and a lot of trimming to the pads.  The best part is that if it doesn't work out, a 46LA, 40LA, 40FP or whatever will go in there with a different set of pads.

The nose is going to get doublers and triplers -- I've cut out fairly small doublers out of 3/32" plywood to tie the engine bearers and the front landing gear mount together.  I just couldn't bear to make a giant doubler out of that heavy plywood to go back to the wing, so once I sheet the fuselage I'll put 1/8" lite ply triplers over the nose back to about the high point of the wing.  That should make a strong-enough front end as long as I don't make a habit of unscheduled contact with the ground.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #73 on: October 28, 2018, 05:07:31 PM »
Outside nose doubler glued & clamped with gravimetric clamp.  I used epoxy mixed with an equal volume of microballoons, to tone down the weight without (hopefully) getting weaker than the wood it's glued to.  Once this is cured I can start fitting the main fuselage sheeting (actually, I can dive into the work-week and make little progress, but that's life).
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Gary Dowler

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Re: Ercoupe Build (slow)
« Reply #74 on: October 29, 2018, 01:01:29 AM »
Looking good, Tim. You going to have it at Roseburg ?  I'll be there, perhaps we can meet in person.  Hoping to have my first scaleproject ready, a PT-26. PT-19 with a canopy, and Canadian license plates.  It's progressing slow though.

Gary
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Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #75 on: October 29, 2018, 08:35:49 AM »
Looking good, Tim. You going to have it at Roseburg ?  I'll be there, perhaps we can meet in person.  Hoping to have my first scaleproject ready, a PT-26. PT-19 with a canopy, and Canadian license plates.  It's progressing slow though.

Well, I'm not sure if it'll be ready for Roseburg in 2019, but yes, I'll have it at the regionals sometime.  Now that I'm part of the corporate machine again I don't have a lot of time to build.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #76 on: October 29, 2018, 07:14:20 PM »
Here I go -- the most foolproof way I've found to make sure I'll never need tail weight.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #77 on: November 04, 2018, 02:04:38 PM »
Putting the sides on the fuselage.  So far the fuselage weight isn't too bad -- if I'm doing my ciphering correctly I'm up to what it would be with 1/2" think 8-pound wood, and because it's built up it's much stiffer.  Overall thickness at the moment is 11/16" or so -- I'm allowed an inch, so I'm OK there.

If you look at the bits laid out you'll see that it's in three pieces, with a tapered piece in the middle.  That' partially because that's what I needed to do to get it to fit, but partially because I had one really heavy sheet of 3/32" balsa -- 11.8 lb/ft3.  So I whacked it into two tapered pieces to go on each side of the fuselage.  I'm hoping that'll make a nice balanced assembly, with the heavy stuff put right where its strength contributes the most to stiffness.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #78 on: November 04, 2018, 08:00:10 PM »
And the triplers!  I only weighed them to torture myself.  The inside tripler (on the top) has a nice layer of Titebond on it, because I put glue on the wrong @#$% side, then scraped it off and tried again.  Oh well; hopefully the covering will stick.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #79 on: November 10, 2018, 01:43:28 PM »
Fuselage assembled, edges sanded, wing cutout cut and fit to the wing.  It's almost time to start running around in the driveway making airplane noises and annoying the neighbors.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Ercoupe Build (slow)
« Reply #80 on: November 11, 2018, 07:05:25 PM »
Tail feathers.  All that's missing from the main structure is the canopy (which is going to be interesting because it's so big and skinny; see this thread)
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Dennis Saydak

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Re: Ercoupe Build (slow)
« Reply #81 on: November 16, 2018, 06:13:25 PM »
Congratulations Tim on a really nice project and build. It's looking great!
Looking forward to seeing the finished model. It will be distinctive in the air.
Just when you think you're getting ahead in the rat race.....you find the rats just get faster! MAAC 13120L


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